System and method for testing a control system of a marine vessel

ABSTRACT

A system for testing a control system in a vessel, comprising: sensors on board the vessel; command input devices on board the vessel to send desired position, course, velocity; an algorithm in the control system for the computation of control signals to the vessel actuators; communication lines for sending simulated command signals from a remote test laboratory to the control system; a simulator including an algorithm for the simulation of the new dynamic state of a vessel model based on a previous state; where the communication line is arranged for sending back the new simulated stare of the vessel model in the form of simulated sensor signals for continued computation to achieve desired position, course, velocity; and where the communication line is sending the response from the control system to the remote test laboratory.

INTRODUCTION

A control system can generally be seen as a system that gives controlsignals to a physical process, and that receives measurements from adevice or a physical process or possibly from other physical processes.The measurements and an algorithm are used to compute the controlsignals so as for the physical process to run as desired. If thephysical process is a motorized vessel, then the control system mayreceive measurements in the form of a vessel position, course andvelocity, and can thereby calculate the control signals to propellersand rudders so that one or more of vessel position, course and velocityare achieved.

Problem Description

The physical process, in this case in the form of a vessel, may beinfluenced by external events like a change in wind, waves and current,or by unexpected events like loss of motor power for one or morepropellers, or failure in the function of a rudder. It Is desired orexpected that the control system for the vessel can handle externalinfluence and external events so as for the vessel to maintain a safestate. A safe state may for example be that that the vessel maintainsthe desired position or velocity, or that it avoids undesired positions(to avoid collision or grounding), that it avoids a situation ofuncontrolled drift, that it maintains a desired course, etc. Moreover,it is expected that the control system in the case of loss of sensorsignals or errors in sensors should not do undesired and unfortunatecompensations like a sudden change in ballast pumping in response toloss of a realistic signal in a roll or pitch sensor, or suddencorrections of an apparent error in position.

Measurements to a Control System

A control system for a ship, with inputs from instruments that givemeasurements, and with outputs to actuators, propelling devices andcontrol devices that are to be given control signals, is shown in FIG. 1and in FIG. 3. This type of control system can receive measurements inthe form of sensor signals from a number of sources:

-   -   roll/pitch/heave sensors,    -   anemometer for measuring relative wind speed and direction,    -   gyro compass,    -   GPS sensors or GPS positioning systems,    -   inertial navigation systems that on basis of acceleration        measurements calculate velocity by integration with respect to        time, and position by double integration with respect to time,    -   hydroacoustic position sensors relative to fixed points at the        sea-floor,    -   taut-wire system of which the direction and length of one or        more tensioned wires from the vessel to points at the seafloor        is observed,    -   command signals for change of course or desired course, desired        position, or desired velocity of the vessel,    -   shaft or and load on propellers and motors,    -   rudder angle sensor,    -   level sensors for loading tanks,    -   ballast level sensors,    -   fuel level sensors,    -   engine state, cooling water temperature, oil pressure, etc.,

The control system is to give control signals to actuators likepropulsors and control devices. The propulsors may be ordinarypropellers, tunnel thrusters or azimuth thrusters, but is some casesalso a mooring system that is designed to pull the vessel to the rightposition. Control signals can also be given to ballast pumps andassociated valves to correct the roll angle or the pitch angle.

Problems Related to Control for Dynamic Positioning, DP.

If the vessel is a petroleum drilling vessel or a petroleum productionvessel, for example a drilling ship or an drilling platform, a petroleumproduction ship or a petroleum production platform, the control systemmay also receive measurements of the heave motion from a heaveaccelerometer, and output a control signal to an active heavecompensation system for a riser, a drill string, cranes, etc. wheremechanical equipment may be connected to the seafloor and of which itmay be essential to compensate for the motion of the vessel, inparticular heave. A normal use of control systems for petroleum activityat sea is for dynamic positioning of the vessel, that is, that thevessel uses actuators like azimuth thrusters to maintain desiredposition during drilling or during production of petroleum. A vesselthat is moored and may rotate about a rotating turret with mooring linesto the seafloor may also have a control system that gives a varyingcontrol signal to propellers or thrusters to assist in keeping thedesired position when the vessel is rotated because the direction of theweather or current changes, so that the thrusters contribute with forcesto compensate for changes in the tension of mooring lines when theforces turn. Similarly, it may be envisaged that that the control systemcan give control signals to increase or decrease tension in the mooringlines of the same reason.

Problems Related to Testing of Control Systems of Vessels.

A ship inspector can visit a vessel and conduct a test on board of thecontrol system. The test on board can be performed by disconnecting orconnecting sensor systems, and to monitor the response of the system indifferent failure situations. However, to make a realistic test of thevessel for conditions that are to be expected, it is necessary to waitfor or to seek weather situations and sea states that rarely occur orthat can be dangerous. It will hardly be considered as an option toexpose the vessel to extreme situations, like abnormally large errors inballast distribution, In order to check If the control system providescontrol signals for correct compensation of the error. Suck kind oftests will normally not be conducted.

It is possible to perform a simulation of sensor data to the controlsystem on board and monitor which control signals that the controlsystem gives to actuators like propellers, rudders and thrusters, butthis requires a local interconnection of the control system to a testsystem and is not done presently as far as the applicants knows. Adisadvantage of visiting the vessel to be tested is often related to along way of travel for the ship inspector, that the ship inspector mustbring equipment for interconnection to the control system inputs formeasurements, and equipment for interconnection to the control systemoutputs for response in the form of control signals that are normallysent to the actuators of the vessel, and in addition a data library thatat least has to include the configuration of the actual vessel to betested. Moreover, the travel time from a vessel that is to be tested andcertified, to a next vessel, can make it difficult for the inspector toperform inspections sufficiently quickly, so that the next vessel willhave to wait longer that necessary, with the economic disadvantagescaused by the waiting, if the vessel cannot be taken into use withouttesting and certification. It may also cause a concealed physical dangerto use a vessel where lack of testing of the control system does notreveal possible errors.

This means that there is a need for more efficient testing of vesselcontrol systems, in particular because the vessels can be geographicallyremote from each other, and in practice not easily accessible for aninspector.

In factory production of a control system it is usual to perform aso-called factory acceptance test (FAT) of the control system (includinghardware and software) where the manufacturer feeds simulated sensordata to the control system and monitors the control signals the controlsystem gives in response. This type of FAT can only reveal errors wheremeasurements from sources that the manufacturer has foreseen to exist,and where the control signals are only for equipment that themanufacturer have foreseen. Thus, it will not be known with certaintyhow the control system will interact with equipment, systems,configurations or situations that the manufacturer of the control systemhas not foreseen. In addition, in a FAT the control system will not betested in the actual constellation where the control system is installedand connected for use on the vessel.

Example of a Practical Problem in Dynamic Positioning.

In dynamic positioning of a vessel (4) that is held in desired positionof propellers, rudders or thrusters of the tunnel or azimuth type, itmay be essential for the operation that the vessel keeps its position.Several events may be undesired. One may experience loss of motor powerfor one or more propellers or rudders, and have to increase the motorpower on the remaining propellers and/or thrusters and perhaps rotatethe remaining rudders or thrusters. One may also experience seriouserrors where the control system loses some of the signals from theconnected sensors so that an undesired incident may occur. The inventorshave knowledge of an instance where a vessel, in this case an drillingplatform, was lying at a fixed position in the open sea and was drillinga drilling hole for a petroleum well in the seafloor, where the drillingplatform held the desired position by means of so-called dynamicpositioning or “DP”, that is, the control system was tuned to hold thevessel in the desired position by means of position measurements andmotor power, without the use of mooring lines to the seafloor. Thedrilling platform was equipped with a double set of DGPS receivers thatcalculate the geographic position of the vessel based on radio signalsreceived from a number of navigation satellites. In addition thedrilling platform was equipped with a double set of hydroacousticposition sensors that measured the position of the vessel with respectto transponders at fixed points on the seafloor. At a given time duringdrilling, with riser connection to the drilling hole and activedrilling, an event occurred so that the DGPS receivers showed a suddenchange in position of about 75 meters, although no such change inposition had actually occurred. The hydroacoustic sensors showed astable position at the desired position over the drill hole. The controlsystem continued to control propellers and rudders, and the drillingplatform was without interruption held at the correct dynamic position,on basis of the signals. However, it turned out that after 5 minutes thedrilling platform suddenly started to move towards the desired positionaccording to the then erroneous DGPS signals. It was necessary todiscontinue the drilling with the associated emergency procedures thatamong other things involved disconnection of the riser and cutting ofthe drill string. This type of situation can involve a risk for blowoutof gas and oil, or pollution by spilling of drilling fluid. This type ofsituation can also present a risk to vessel and crew. This type ofdiscontinued DP-drilling may thus be very expensive to start up again.The applicants assume that the initial sudden change of the positioncalculated by the DGPS receivers can have been caused by disturbances inthe signal transmission from the GPS satellites to the receivers, or bya situation with an insufficient number of available satellites. Theloss of the DGPS signal can have been ignored by the control systembecause of quality conditions in the software of the control system thatrequire that such a calculated position must have been stable in thepreceding 5 minutes to be considered to be real. In this way suddenchanges in position due to erroneous signals are avoided. However, thenew and changed, but nevertheless stable position calculated from theDGPS receivers can after 5 minutes have been regarded as stable andtherefore reliable by the control system, and may have been given ahigher priority than the measurements from the hydroacoustictransponders. This may be the reason why the control system attempted tocontrol the drilling platform to the new position that the controlsystem had evidently interpreted as the desired position, althoughdrilling was in progress and the hydroacoustic measured positionindicated that the position should be kept unchanged.

Problems Related to Changed Configurations in a Vessel:

Reprogramming of a Control System

After a control system has been put to use in a vessel there will inmany cases be a need for reprogramming or modification of the softwarein the control system. The purpose for doing this can be a need forchanging numerical values related to alarm limits and acceptablevariation in a sensor signal in the algorithm of the program, or it canbe a need for the introduction of new tests and functions in the controlsystem. When the reprogramming or modification of the software iscompleted there is a need for testing the control system to see if thechanges have given the intended effect, and to check whether new andunintended errors have appeared as a consequence of the modifications.At present, satisfactory test equipment and procedures are not availablefor the testing of the control systems on a vessel after such changes.

Modifications in an Existing Control System, e.g. when Replacing Cranes.

Marine operations, related to oil and gas exploration and production,are made by vessels with cranes for installation and replacement ofmodules on the seafloor. This type of cranes has control systems thatcompensate for the vertical motion of the vessel. The mode of operationand the function of the crane in safety-critical situations will to alarge extent depend on the detailed design of the software of thecontrol system, which will vary from one crane to another. Procedureshave been established for the testing of the mechanical design of suchcranes. In contrast to this there are no established systems or methodsfor the testing of the software of the crane control systems. The reasonfor this is that the response of the crane will depend on the sea stateand the motion of the vessel in addition to the mechanical design andthe control system of the crane. A required detailed testing of a cranesystem on a vessel should therefore involve both the dynamics of thevessel including the relevant control systems of the vessel, and inaddition, the dynamics of the crane including the control system of thecrane.

Repair/Replacement of Sensors for a Control System.

When sensors for a control system are replaced or modified, there is aneed for adjustment of alarm limits for limits for acceptable variationsin the sensor signals. It is customary for a control system to haveredundant sensor systems so that several sensors may be used to measurethe same physical quantity. As an example of this, the position of avessel can be measured by inertial sensors, two or more GPS-receiversand two hydroacoustic sensor systems. From these measurement data theposition of the vessel is determined by means of an algorithm in thecontrol system. This algorithm will depend on the properties of thevarious sensors with respect to accuracy and properties like long termstability versus accuracy under rapid position variations. Replacementor modification of a sensor introduces the need for testing of the totalsensor system to investigate whether the resulting combination ofsensors provides acceptable position measurements for use in a controlsystem.

Repair/Modification/Replacement of Actuators.

After replacement or modification of an actuator, a control system maygive a significantly different response for the vessel. The reason isthat a new or modified actuator may give a different control action tothe vessel than what was assumed in the development of the controlsystem. An example of this is in the use of thrusters for dynamicpositioning, where the relation between the shaft speed of the thrusterand the thrust must be known when the control system is tuned. If athruster is changed, then the relation between the shaft speed of thethruster and the thrust may be changed, and it will be necessary to testthe vessel with the control system to investigate if the system stillperforms satisfactorily.

Thus there is a need for a more effective testing of vessel controlsystems, also in the cases where the vessel has been modified from itsprevious configuration, and where old and new components of the vesselhave not been previously combined, and has to be tested in the newcombination.

Known Art in the Field.

The U.S. Pat. No. 6,298,318 “Real-time IMU signal emulation method fortest of guidance navigation and control systems” describes an emulationmethod for testing of a plane by emulating the motion using a so-called6 degrees-of-freedom (6 DOF) flight simulator and where signals from aso-called inertial navigation module to a “guidance, navigation andcontrol” system on board the aircraft are generated by simulation. ThisUS patent does not discuss problems related to dynamic positioning of avessel in drilling operations or some other form of stationaryoperation, it does not mention the use of cranes, navigation ofconnected underwater equipment, integration of hydroacoustic positioningequipment, problems related to ballasting, and does not consider oceanwaves. A ship will normally not have 6 DOF, but instead 3 DOF as it hasrestoring action in heave/roll/and pitch motion.

The U.S. Pat. No. 5,023,791 “Automated test apparatus for aircraftflight controls” describes an automated test apparatus for the testingof flight control systems of an aircraft as part of an integrated systemfor testing a plurality of flight control systems. The automated testapparatus includes a system controller having memory for storingprogrammed instructions that control operation of the automated testapparatus, and for storing resulting flight controls system test data.The automated test apparatus includes a keyboard, a touch-screen, and atape drive for entering programmed instructions and other informationinto the automated test apparatus, and for outputting test data from thesystem controller. Instruments included in the automated test apparatusand controlled by the system controller generate test signals that areinput to the aircraft's flight controls system, and monitor resultingtest data signals that are produced by the flight controls system. Theautomated test apparatus is connected by an interface cable to anonboard central maintenance computer included in the aircraft. Thecentral maintenance computer includes a non-volatile memory that isprogrammed to run onboard tests of the flight controls system, and iscontrolled by the system controller during testing in accordance withthe programmed instructions to run the onboard tests.

U.S. Pat. No. 5,541,863 “Virtual integrated software testbed foravionics” describes a virtual integrated software testbed for avionicswhich allows avionics software to be developed on a host computer usinga collection of computer programs running simultaneously as processesand synchronized by a central process. The software testbed discloseduses separate synchronized processes, permits signals from an avionicsdevice to be generated by a simulation running on the host computer orfrom actual equipment and data bus signals coming from and going toactual avionics hardware is connected to their virtual bus counterpartsin the host computer on a real-time basis.

U.S. Pat. No. 5,260,874 “Aircraft flight emulation test system”describes an aircraft test system that generates stimuli that emulatethe stimuli received by an aircraft when in flight. The aircraft testsystem includes a number of instruments for generating the number ofprocessor-controllable instruments for generating stimuli received by anaircraft when in flight. The system also includes a number ofinstruments that monitor the response of the various aircraft componentsto the stimuli to which the aircraft is exposed. A processor in responseto the output signal from the aircraft components directs the stimuligenerating instruments to produce stimuli that emulate those received bythe aircraft as it moves through the air. The system thus generates aninitial set of stimuli similar to what an aircraft would be exposed towhen in flight; monitors the response of the aircraft to the stimuli towhich it is exposed; and, in response generates an updated set ofstimuli to the aircraft. The system also records the response of theoutput responses of aircraft components so that they could be monitoredby personnel charged with insuring that the aircraft is functioningproperly. The system can also be used to train flight crews since it canbe used to place the aircraft “in the loop” during a flight emulation.

U.S. Pat. No. 6,505,574 “A vertical motion compensation for a crane'sload” describes a method and a system for reducing sea state inducedvertical motion of a shipboard crane's load using winch encoders, boomangle sensor, turning angle sensor and motion sensor that all feedmeasurements into a central processor that controls the crane on basisof the measurements and the commands from a crane operator.

A Solution to the Problem, Short Summary of the Invention.

A solution to the problems described above in connection with testing ofcontrol systems for ships is, according to the invention, a method fortesting of a control system in a vessel, where the control systeminvolves control and monitoring of the vessel with control signals toone or more actuators, where the method comprises the following steps:

acquisition in real time of sensor data to the control system from oneor more sensors over a first sensor signal line to the control system;

acquisition of command signals to the control system from a commandinput device over a second signal line or command signal line to thecontrol system;

computation in a control algorithm in the control system on basis of oneor more of the acquired sensor data and command signals, and sending ofthe control signals over a third signal line to the actuators.

The novelty of the invention comprises the following steps:

disconnection of one or more sensor signals from one or more of thesensors or of command signals from one or more of the command inputdevices, so that the selected sensor signals or command signals are notsent to the control system, and replacement of one or more of thedisconnected sensor signals or command signals, by correspondingsimulated sensor signals or command signals that are generated in aremote test laboratory with respect to the vessel and sent over acommunication line through one or more of the signal lines to thecontrol system;

continued computation in the control system on basis of real and/orsimulated sensor signals or command signals of control signals, and

transmitting the control signals over a communication line to the remotetest laboratory.

In a preferred embodiment of the invention the method will includesimulation in a simulator in the remote test laboratory by means of analgorithm of the dynamic new state of a vessel on basis of the controlsignals.

Additional steps of the method of the invention are found in thedependent patent claims.

When the testing of the control system is completed, the communicationline between the vessel and the remote test laboratory is disconnected,and the sensors and the command input devices are connected to thecontrol system in the regular way, and the control system outputs forcontrol signals are connected to the actuators, for normal operation ofthe control system in the vessel.

The invention also includes a system for testing of a control system ina vessel, where the control system is arranged to control and monitorthe vessel, comprising the following steps:

one or more sensors on board the vessel arranged to send one or moresensor signals over a signal line to the control system,

command input devices on board the vessel arranged to send desiredposition, course, velocity etc. over a command signal line to thecontrol system,

an algorithm in the control system for the computation of controlsignals to the vessel actuators on basis of sensor signals, commandsignals, for sending of the control signals over a signal line to theactuators, in which the novelty of the system comprises the followingsteps:

one or more communication lines for transmission of one or moresimulated sensor signals and/or simulated command signals from a remotetest laboratory to the control system;

a simulator including an algorithm for the simulation of a new dynamicstate of a vessel model based on a previous state, control signals, anddynamic parameters of the vessel,

where the communication line is arranged for transmitting back the newsimulated state of the vessel model in the form of simulated sensorsignals to the control system, for continued computation in the controlsystem on basis of the real and/or simulated sensor signals or realand/or simulated command signals, of control signals to achieve at lastone of desired position, course, velocity etc., and

where the communication line is arranged to transmit the response of thecontrol system in the form of control signals as control signals to theremote test laboratory.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the enclosed drawings in FIG. 1 to FIG.7. The drawings are meant to illustrate the invention and shall not beconstrued to restrict the invention, which shall only be restricted bythe attached claims

FIG. 1 illustrates a vessel with a control system. The control systemreceives measurements of position, course and velocity from navigationalinstruments and receives commands from a position specification device,the control panel of the control system, a velocity specificationdevice, and a velocity or shaft speed specification device for thepropeller or for possible thrusters. The control system can also receivemeasurements of relative wind direction and relative wind speed form ananemometer, and it can receive or calculate information about sea state,that is, wave elevation, roll period, pitching, etc. The control systemcan be designed to sequentially output shaft speed to propellers andangles to rudders so that the desired position, course and velocity areachieved.

FIG. 2 illustrates a FAT of a control system for a vessel, where thecontrol system is connected to an interface with simulated sensorsignals and where the control system gives response in the form ofcontrol signals to (not connected) actuators.

FIG. 3 illustrates a known control system for a ship, with the connectedsensors, command input devices and actuators of the control system.

FIG. 4 a illustrates the basic idea of the invention, in which a vesselsimulator is arranged in a remote simulator location, with a logger,both connected through a first real-time interface at the simulatorlocation, with one or more communication channels for real-time control,simulation and logging, to one or more real-time interfaces forreal-time control, simulation and logging which is further connected toa control system, e.g. a control and monitoring system on at least onevessel. The simulator location may be e.g. at a so-called class societyon land.

FIG. 4 b illustrates a vessel with a control system where one or more ofthe real sensor signals are replaced by simulated sensor signals over acommunication line to and from a test laboratory, and where one ore moreof the control signals from the control system to the actuators of thevessel are sent back over a communication line to the test laboratory,preferably instead of being sent to the actuators of the vessel.

FIG. 4 c illustrates a vessel where a set of sensors for pitch, roll,wind speed, wind direction, GPS position sensors, DGPS position sensors,hydroacoustic position sensors, etc., that are normally arranged to givemeasurements to the control system of the vessel, are replaced bysimulated measurements from a remote test system via one or morecommunication lines, and where the control system responds to thesimulated measurements where the response would normally give controlsignals to the actuators of the vessel, like e.g. propellers, rudders,tunnel thrusters, azimuth thrusters, and where the response is sent viaa communication line to a remote test laboratory where a vesselsimulator e.g. in the form of an algorithm calculates a the dynamicbehavior of a simulated vessel in response to the control signal fromthe remote control system in the vessel, and sends the new state of thevessel back to the remote system, for a new response in the form ofupdated control signals, etc.

FIG. 5 illustrates an overview of the vessel motions in the form ofroll, pitch and heave.

FIG. 6 illustrates an overview of the vessel motions in surge, sway andyaw, which are important in connection with dynamic positioning, e.g.,in connection with oil drilling without mooring (or in some cases withmooring).

FIG. 7 shows a sketch of a relevant problem for use of the inventionwhere a control system is used to control a drilling platform underdynamic positioning while it is drilling, where the actual position andthe desired position of are marked with boldface “x”.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The invention includes a system for and a method for testing of acontrol system (2) on a vessel (4), e.g. a ship, a drilling platform, apetroleum production platform, in real time over a communication channel(6), as shown in an overview in FIG. 4 a, and in more detail in FIGS. 4b and 4 c. The control system (2) may include control and monitoring ofthe vessel (4). Testing of the control system (2) may include thesimulation of normal states and extreme states and normal changes tosuch normal and extreme states for the vessel (4), for example ordinarymovement in a simulated calm sea state (H₁). In addition, one maysimulate ordinary movement in a simulated extreme sea state (H₂),failure situations with e.g. loss of motor power on a single propeller(16) where the vessel has only this single propeller (16), withsubsequent dynamic simulation of rotation away from a desired course (7b) and drift away from a desired position (7 a). One may also simulatethe loss of one or more propellers (16 a, 16 b, . . . ) where the vessel(4) has one or more propellers (16 b, 16 c, . . . ) that stillfunctions, and study how the vessel will react to the loss of one ormore propellers.

In the following a brief description is given of the system as amaterial device illustrated in FIGS. 4 a, b and c, for intervention froma remote laboratory (40) to control systems (2) in one or more vessels(4 a, 4 b, 4 c, . . . ).

The system according to the invention is arranged for the testing of acontrol system (2) in a vessel (4), where the control system (2) isarranged to control and monitor the vessel (4). The system according tothe invention comprises the following features:

One or more sensors (8) arranged on board the vessel (4) are arranged tosend one or more sensor signals (7) over a signal line (12) to thecontrol system (2).

Command input devices (10) on board the vessel (4) are arranged to senda desired position, course, velocity (9) etc. over a command signal line(11) to the control system (2).

An algorithm (31) in the control system (2) is arranged for computingcontrol signals (13) to the vessel actuators (3) based on the sensorsignals (7) and/or the command signals (9), for sending of the controlsignals (13) over a signal line to the actuators (3).

One or more communication lines (6) is arranged to send one or moresimulated sensor signals (7′) and/or simulated command signals (9′) froma remote test laboratory (40) to the control system (2). The remotelaboratory may be on land, and equipment for real-time communicationmust be available both in the laboratory and on each vessel that is tobe tested.

The remote laboratory includes a simulator (30) including an algorithm(32) for the simulation of the new dynamic state (7′) of a vessel model(4′) based on previous state (7, 7′), control signals (13, 13′), anddynamic parameters (5) for the vessel (4).

The communication line (6) is arranged for sending back the newsimulated state of the vessel model (4′) in the form of sensor signals(7′) to the control system (2), for continued computation in the controlsystem (2) on basis of the real and/or simulated sensor data (7,7′) orreal and/or simulated command signals (9,9′), of control signals (13) toachieve at least one of desired position, course, velocity etc.

The communication line (6) is arranged for sending of the response ofthe control system (2) in the form of the control signals (13) ascontrol signals (13′) to the remote test laboratory (40).

The control signals (13) include signals (13 a, 13 b, 13 c) in the formof shaft speed (13 a, 13 b) for one or more propellers (16) or thrusters(17), and rotation angles (13 c) for rudders (18) or thruster (17) andpossibly other actuators.

The sensors (8) include one ore more of the following:

-   -   position measuring devices (8 a), to determine the vessel        position (7 a), such as GPS receivers (8 a), hydroacoustic        position sensors (8 h), integrating acceleration sensors, etc.;    -   course measuring devices (8 b), to determine the vessel course        (7 b), e.g. a gyrocompass or some other compass.    -   a speed sensor (8 c) or single integrating acceleration sensor        to determine the velocity (7 c);    -   an anemometer (8 d, 8 e) to indicate the (relative) wind speed        (7 d) and wind direction (7 e);    -   a roll angle sensor (8 f) to indicate the roll angle (7 f);    -   a pitch angle sensor (8 g) to indicate the pitch angle (7 g).

In a preferred embodiment of the invention the system is equipped with aknob or switch (15 a) arranged to disconnect one or more sensor signals(7) from the signal line (12) to the control system (2). In addition,the system according to the invention may be provided with a secondswitch (15 b) arranged to disconnect one or more of the command signals(10) from the signal line (11) to the control system (2), and alsoprovided with a third switch (15 c) arranged to disconnect one or moreof the control signals (13) from the signal line (14) from the controlsystem. In this way the switches (15) can be used to fully or partiallyisolate the control system (2) from signals to and from the rest of thevessel. The control system (2) can still be connected to the regularelectrical power supply on board.

The system implies as usual that the dynamic parameters (5) of thevessel enter into the algorithm (31) of the control system (2) for thecomputation of the control signals (13) to the actuators (3).

According to a preferred embodiment of the invention the system isarranged so that the remote test laboratory (40) is equipped with asimulator (30) with an algorithm (32) arranged to simulate the state ofa vessel on basis of an initial state represented by completely orpartially simulated measurements (7, 7′) and control signals (13, 13′)from the control system (2).

According to a preferred embodiment of the invention the communicationline (6) is arranged for sending of one or more simulated sensor signals(7′) from the remote test laboratory (40) which further is arranged tobe connected to and disconnected from a first real-time interface (6 a),on the remote test laboratory (40). In the same way the communicationline (6) may be arranged for being connected to and disconnected from asecond real-time interface (6 b) on the vessel (4), and where the secondreal-time interface is arranged for being connected through the switch(15 a) to the signal line (11) to the control system (2).

According to a preferred embodiment of the invention a simulated commandinput device (10′) is arranged for sending of simulated command signals(9′) from the remote test laboratory (40) over the real-time interface(6 a), and over the communication line (6) and over the real-timeinterface (6 b) to the control system (2).

The system can be arranged so that all of or parts of the algorithm (31)in the control system (2) can be modified, calibrated, or replaced, overthe communication line (6) from the remote test laboratory. According tothe invention the test laboratory includes a data logger (15) forlogging of the response (13′, 19′) from the control system (2) to themeasurements (7, 7′).

Description of the Method for Testing of the Control System.

The system described above is arranged for being used in a method fortesting of a control system (2) in a vessel (4). The control system (2)includes control and monitoring of the vessel (4) with control signals(13) to one or more actuators (3). The method according to the inventioncomprises the following steps:

Acquisition in real time of sensor signals (7) to the control system (2)from one or more sensors (8) over a first sensor signal line (12) to thecontrol system (2).

Acquisition of command signals (9) to the control system (2) from acommand input device (10) over a second signal line or command signalline (11) to the control system (2).

Computation in a control algorithm (31) in the control system (2) onbasis of one ore more of the acquired sensor signals (7) and commandsignals (9), and the dynamic parameters (5) of the vessel, and sendingof the control signals (13) over a third signal line (14) to theactuators (3).

The novelty of the invention involves the disconnection of one or moresensor signals (7) from one or more of the sensors (8) or of commandsignals (9) from the command input devices (10), so that the selectedsensor signals (7) or command inputs (9) do not reach the control system(2), and at the same time replacement of one or more of the disconnectedsensor signals (7) or command signals (9), with corresponding simulatedsensor signals (7′) or command signals (9′) that are generated on aremote test laboratory (40) with respect to the vessel (4). Thesimulated signals (7′, 9′) are sent over a communication line (6)through one or more of the signal lines (12, 14) to the control system(2) from the remote test laboratory.

Computation of the control signals (13, 13′) will continue in the usualway in the control system (2) on basis of real and/or simulated sensorsignals (7 a or 7 a′, 7 b or 7 b′, 7 c or 7 c′, . . . ) or commandsignals (9 a or 9 a′, 9 b or 9 b′, 9 c or 9 c′, . . . ).

The control signals (13′) that are generated by the control system canthen be sent over the communication line (6) to the remote testlaboratory (40).

According to a preferred embodiment of the method the method will theninclude simulation in a simulator (30) in the test laboratory (40) bymeans of an algorithm (32) of a new dynamic state of a vessel model (4′)on basis of the control signals (13′). In this way a test on the controlsystem (2) can be performed from the remote test laboratory (40) on avessel independently of where the vessel is placed in the world. Thesimulation algorithm must take into account the time delay caused by theuse of the communication line (6).

According to the method according to the invention the remote testlaboratory (40) that is involved in the testing of the control systemcan be located on land, and the vessel (4 a, 4 b, 4 c, . . . ) that istested is a long distance away from the test laboratory, typicallybetween 1 and 20000 km, and where the vessel (4 a, 4 b, 4 c, . . . )that is tested is in a nearby harbor, in a distant harbor, in a dock orin a yard, at anchor, or in the open sea.

When the testing of the control system is completed, the communicationline between the vessel and the remote laboratory is disconnected, andthe regular sensor signals and the regular command signals to thecontrol system are reconnected, and the control signals from the controlsystem are reconnected to the actuators, for normal operation of thecontrol system in the vessel.

According to the preferred embodiment of the invention the sensorsignals (7) comprise one or more of the following sensor parameter fromsensor (8):

-   -   The vessel position (7 a) from position sensors (8 a), such as        GPS-receiver (8 a), hydroacoustic position sensors (8 h),        integrating acceleration sensors, etc.    -   course (7 b) fro course sensors (8 b), e.g. a gyrocompass or        another compass,    -   velocity (7 c) from a velocity sensor (8 c) or a        single-integration acceleration sensor;    -   wind speed (7 d) an wind direction (7 e) from a anemometer (8 d,        8 e),    -   roll angle sensor (7 f) from a roll sensor (8 f),    -   pitch angle sensor (7 g) from a pitch sensor (8 g).

According to the preferred embodiment of the invention the controlsignals (13) include signals (13 a, 13 b, 13 c) in the form of shaftspeed of one or more propellers (16) or thrusters (17), and angles forrudders (13 c) or thrusters (17) and possibly other control devices toachieve one or more of desired position (9 a), course (9 b), velocity (9c).

The method may be used to calculate control signals to one or morepropellers (16 a, 16 b, 16 c, . . . ), and control devices (18) mayinclude one or more rudders (18 a, 18 b), and it may include one or morethrusters (17).

The command input device (10) will at least include a positionspecification device (10 a), a steering wheel (10 b), a velocityspecification device (10 c), or a device for specification of desiredinclination angle, pitch angle, heave compensation, etc. (10 x) thatgive a command signal (9) of one or more of desired position (9 a),desired course (9 b), and desired velocity (9 c) or another desiredstate (9 x), e.g. desired roll angle, desired pitch angle, desired heavecompensation, etc.

According to a preferred embodiment of the invention the method includesthat the remote test laboratory (40) is used to verify that the controlsystem (2) on basis of the simulated sensor signals (7′) in the test,and possibly remaining real sensor signals (7), the simulated commandsignals (9) and possibly remaining real command signals (9) givescontrol signals (13, 13′) that will lead to a desired state of thevessel, and where the control system (2) is certified on basis of thistest.

The dynamic parameters (5) of the vessel may involve the mass (m), theaxial moments of inertia, and the mass distribution of the vessel, thehull parameter that describe the geometry of the hull, as explainedbelow. Disconnection of the sensor signals (7) from the sensors (8) tothe control system (2) can be done by means of a switch (15 a) on thesignal line (12). Disconnection of command signals (9) from the commandinput devices (10) to the control system (2) may be made by means of aswitch (15 b) on the signal line (11).

According to a preferred embodiment of the method according to theinvention, failure situations cay be tested by disconnection of one ormore of selected sensor signals (7) or command signals (9) at the timeto simulate breakdown of components, and where the response of thecontrol system (2) in the form of control signals (13, 13′) and statussignals (19, 19′) are logged in a logger (15) in the test laboratory(40).

Failure situations can also be tested by changing measurements or bygenerating disturbances in selected sensor signals (7′), or bygenerating external disturbances like weather, wind, electrical noise tothe measurements (7′) that are sent from the remote test laboratory (40)to the control system (2) in the vessel (4), and where the response ofthe control system (2) in the form of control signals (13, 13′) andstatus signals (19, 19′) are logged on a logger (15) in the testlaboratory (40) According to a preferred embodiment of the methodaccording to the invention new software for the control system (2) inthe vessel (4) can be transmitted from the test laboratory (40) over thecommunication line (6).

After the execution of the method according to the invention, in whichthe test laboratory (40) on basis of the test of the control system (2)and the test results can approve the control system (2), the testlaboratory (40) can certify the control system (2) for use in regularoperation of the vessel (4).

One of the advantages of the proposed remote testing according to theinvention is that one will have a much larger flexibility in the testingof the software and the control system (2) in its entirety undersimulated failure situations and under a simulated extensive spectrum ofweather loads than what would be the case under conventional testing andcertification. At the same time, one avoids the disadvantages andlimitations of previously used methods for testing of vessel controlsystems, namely travel distance, time consuming travels, high cost oftravel, time for rigging of equipment for testing, etc. With theproposed invention it is possible to test and certify far more vesselsthan previously, with a lower number of operators.

Example of Testing of a Control System on a Drilling Vessel.

The present invention can be used to test if a control system asmentioned above will indeed function in a safe and reliable way. One mayimagine the following example: It is desired to test a control system(2) in a drilling vessel (4) as illustrated in FIG. 7. Drilling may beterminated before the test so that potential errors in position underthe test with simulated dynamically positioned drilling will not havenegative consequences. The drilling vessel (4) includes a control system(2) that corresponds to what is sketched in FIGS. 4 a, b and c, and isin the same way connected through a real-time interface (6 b) and acommunication line (6) and through a real-time interface (6 a) to aremote test laboratory (4) as shown in the drawings. The control system(2) comprises control and monitoring of the drilling vessel (4) withpropulsion devices (16) like propeller (16 a, 16 b, 16 c, . . . ) orthrusters (17), and control devices (18) like rudders (18), thrusters(17) in the form of tunnel thrusters and azimuth thrusters. Thethrusters (17) can act both as propulsion devices (16) and controldevices (18). Under the simulated drilling it is desirable that thedrilling vessel (4) is at a stationary position (9 a) with a smallestpossible position deviation, and with a course (7 b) and velocity (7 c)that only compensate for the weather in the form of its influence onwind, waves and current. The method for dynamic positioning in agreementwith known methods may comprise the following steps that can be executedsequentially:

The control system (2) acquires in real time the sensor data (7) fromone or more sensor parameters, such as the measured vessel position (7a) from position sensors (8 a), e.g. DGPS receivers, and course (7 b)from course sensors (8 b) like gyrocompasses, etc.

The control system (2) acquires command signals (9) from a command inputdevice (10), for example a so-called joy-stick panel, including at leasta position specification device (10 a), a wheel (10 b), a velocityspecification device (10 c), that give command signals for one or moreof desired position (9 a) as indicated in FIG. 7, desired course (9 b)in the form of angle for rudder or thrusters, and desired speed (9 c) inthe form of shaft speed for propellers (16) and thrusters (17).

The sensors (8) transmit the sensor signals (7) over a first sensorsignal line (12) to the control system (2).

The command input device (10) sends the command signals (9) over asecond signal line or command signal line (11) to the control system(2).

The control system (2) then calculates sequentially on basis of one ormore of the acquired sensor signals (7 a, 7 b, 7 c, . . . ) and commandsignals (9 a, 9 b, 9 c, . . . ) and possibly a set of required dynamicparameters like mass (m) and axial moments of inertia (M₁, M₂, . . . )for the vessel (4), of the required shaft speed (13 a) for propellers(16) and angle (13 c) for rudder (18) and possible other control devicesto maintain and restore one or more of desired position (9 a), course (9b), velocity (9 c) etc.

The control system (2) then sends the control signals (13 a, 13 b, 13 c,. . . ) including the required shaft speed (13 b) from the controlsystem (2) over a third signal line (14) to control the shaft speed (13a) for propellers (16) and/or thrusters (17), and angles (13 c) forrudders (18) and/or thrusters (17).

The novelty of the invention can be executed with the following steps:

By means of a knob or a switch (15 a) on the signal line (12), one ormore of the sensor signals (7) from one ore more of the sensors (8) aredisconnected from the control system (2), and/or by means of a switch(15 b) on the signal line (11) one or more of the command signals (9)from the control input device (10) are disconnected from the controlsystem (2).

One or more of the disconnected sensor signals (9), e.g. the measuredposition (7 a) or course (7 b), or one or more of the disconnectedcommand signals (9), e.g. desired position (9 a) or desired course (9b), are replaced with the corresponding simulated sensor signals (7′),e.g. simulated measured position (7 a′) or simulated measure course (7b′), or simulated corresponding command signals (9′), e.g. simulateddesired position (9 a′) or simulated desired course (9 b′), by blindingone or more of the signal lines (12, 14), where the simulated sensor andcommand signals (7, 9) are generated in a remote test laboratory (40)with respect to the vessel (4) and are sent over a communication line(6) through one or both of the switches (15 a, 15 b) and into one ormore of the signal lines (12, 14). In this case one may blind the sensorsignals (7 a) from the DGPS receivers (8 a) and replace these by a new,wrong and deviating position a given distance away from the position (9a) where the vessel (4) actually is.

The control system (2) then performs sequential continued computationsof the required shaft speed (13 b) for propellers (16) and angle (13 c)for rudders (18) and other control devices to achieve at least one ofdesired position, course, velocity, etc. on basis of the input and/orsimulated sensor signals (7 a or 7 a′, 7 b or 7 b′, 7 c or 7 c′, . . . )and command signals or simulated command signals (9 a or 9 a′, 9 b or 9b′, 9 c or 9 c′, . . . ) and the required vessel parameters (5). Thecomputed response, the so-called control signals (13) from the controlsystem (2) to the actuator (3), like for example the control signal (13a) for the control of propellers (16) and the angle (13 c) of rudders(18), can be disconnected or blinded by means of a third switch (15 c)so that the control signals (13) do not control the propellers (16) orthe rudders (18) during the test, but are instead sent over thecommunication line (6) to the remote laboratory (40).

The control system (2) may then be regarded as a “black box” (2) where achange is simulated in at least one of the sensor signals (7) to the“black box” (2), and where the “black box” (2) responds with a controlsignal (13). In the case of the drilling vessel (4) mentioned in theintroduction, where there was an error in the DGPS signals, one wouldexperience after 5 minutes that the control system (2) would suddenlyattempt to control the propellers, thrusters and rudders of the vessel(4) in order to move the vessel to a new position that the controlsystem would suddenly regard as correct because it had been given asstable and wrong for 5 minutes.

The Motion of a Vessel and the Simulation of this Motion.

The motion of a vessel (4) is described in terms of the velocity of theship in surge, sway and yaw, by the position of the center of mass, andby angles in roll, pitch and yaw, see FIG. 5. A vessel will be exposedto forces and moments that influence the motion of the vessel. Theseforces and moments are due to excitation from wind, current and waves,from the use of actuators (3) like propellers (16), thrusters (17) andrudders (18), from hydrostatic forces that correspond to spring forceaction due to angles in roll and pitch and position in heave, and fromhydrodynamic forces that are related to the velocity and acceleration ofthe vessel (4). Forces and moments that act on a vessel (4) depend onthe vessel motion, whereas the motion of the vessel can be seen as aconsequence of the forces and moments that act on the vessel. For avessel or ship the geometry of the hull, the mass and the massdistribution will be known. In addition estimates of the hydrodynamicparameters of the ship will be known. When the motion of the vessel isgiven, then forces and moments that act on the ship can be calculated ina simulator (30), for example by use of an algorithm (32). Theacceleration and angular acceleration of the vessel may then becalculated from the equations of motion for the vessel, which are foundfrom Newton's and Euler's laws. Such equations of motion are describedin textbooks. In the equations of motion the following parameters appear

-   -   The vessel mass,    -   the position of the center of mass,    -   the position of the center of buoyancy,    -   the moments of inertia of the vessel;    -   the hull geometry, including length, beam and draft;    -   hydrodynamic added mass,    -   hydrodynamic potential damping,    -   viscous damping,    -   parameters related to restoring forces and moments on the hull        due to motion in heave, pitch and roll,    -   parameters relating the amplitude, frequency and direction of        wave components to the resulting forces and moments on the hull.    -   Moreover, the equations of motion include mathematical models        for actuator forces from propellers (16) as a function of the        propeller speed and pitch, forces from rudders (18) as a        function of the rudder angle and the vessel speed, and forces        from thrusters (17) as a function of the thruster speed and        direction. The following procedure can be used to compute the        motion of a vessel (4, 4′) over a time interval from T0 to TN:

Suppose that the motion of the vessel is given at the initial timeinstant T0, and the forces and moments are calculated at this timeinstant. The acceleration and angular accelerations of the vessel attime T0 can then be computed from the equations of motion for the vessel(4, 4′). Then numerical integration algorithms can be used to calculatethe motion of the vessel at time T1=T0+h, where h is the time step ofthe integration algorithm. For a vessel the time step h will typicallybe in the range 0.1–1 s. When the motion of the vessel (4, 4′) at timeT1 is computed, the forces and moments at time T1 can be computed, andthe acceleration and angular acceleration at T1 are found from theequations of motion. Again, using numerical integration the motion ofthe vessel at time T2=T1+h is computed. This procedure can be repeatedat each time instant TK=T0+h*K until time TN is reached.

The waves that act on a vessel are described as a sum of wave componentswhere one wave component is a sinusoidal long-crested wave with a givenfrequency, amplitude and direction. For a given location at sea theprevalent distribution of amplitude and frequency of the wave componentswill be given by known wave spectra like the JONSWAP or ITTC spectra,where the intensity of the wave spectrum is parameterized in terms ofthe significant wave height. The resulting forces and moments acting onthe vessel will be a function of the amplitude, frequency and directionof the waves, and of the velocity and course of the vessel. Forces andmoments from wind will be given by wind speed, wind direction, vesselvelocity and the projected area of the ship above the sea surface as afunction of the vessel course relative to the wind direction. Forces andmoments from current will be given by the current speed, currentdirection, the projected area of the hull under the sea surface, and bythe vessel velocity and course relative to the current direction.

Dynamic Positioning—DP:

In dynamic positioning, so-called DP, the vessel (4) is controlled inthree degrees of freedom (DOF). The desired position in x and y and incourse are given as inputs from an operator using keyboard, roller ball,mouse or joy-stick on a control panel (10). A control system (2) is usedto compute the required actuator forces in the surge and swaydirections, and the actuator moment about the yaw axis so that thevessel achieves the desired position and course. The control system (2)also includes actuator allocation, which involves the computation ofpropeller forces, rudder forces and thruster forces corresponding to thecommanded actuator forces and moments. The control system (2) isimplemented through the running of an algorithm (31) on a computer onboard the vessel (4). This algorithm (31) compares the desired position(9 a) and course (9 b) with the measured position and course (7 a, 7 b),and of basis of this the algorithm computes the required actuator forcesand moments using control theory and found in textbooks. In addition thealgorithm includes an allocation module where propeller forces, rudderforces and thruster forces are computed. The position and course aremeasured by DGPS sensors, gyrocompasses, hydro-acoustic sensor systemswhere transponders are laced on the sea floor, and taut-wires where theinclination of a taut wire fixed on the sea-floor is measured.

Components

-   1: --   2: Control system-   3: Actuators (propeller 16, thruster 17, rudder 18)-   4: Vessel, ship, drilling vessel, drilling platform, production    platform, or other sea-going vessel.-   4′: Simulated vessel, vessel model in simulator (30) or the    simulator algorithm (32).-   5: The dynamic parameters of the vessel. 5 a: mass m, 5 b: 5 c:    position of center of mass, 5 c, 5 d, 5 e moments of inertia about    the vessel axes, mass distribution, hull parameters, etc.-   6: Communication line, including a first real-time interface (6 a)    in the remote test laboratory (40), and a second real-time interface    (6 b) on a first vessel 4 a, (6 c) on a second vessel (4 b), etc.-   7: Sensor signals from sensors (8): 7 a: position, 7 b: course, 7 c:    velocity, 7 d: wind speed (rel), 7 e: wind direction (rel), 7 f    pitch angle, 7 g, roll angle, 7 h: hydroacoustic (relative) position    with respect to transponders on the seafloor, 8 i, GPS/inertial    position and course.-   8: Sensors: 8 a: position sensor; 8 b: (gyro)compass, 8 c: velocity    sensor, 8 d: wind speed sensor, 8 e: wind direction sensor, 8 f:    pitch sensor, 8 g, roll sensor, 8 h: hydroacoustic position sensor,    8 i: “Seapath 200” GPS/inertial sensor of position and course.-   9: Command signals from command input device (10): 9 a: desired    position, 9 b: desired course, 9 c: desired velocity, etc.-   10: Command input device: Position specification device 10 a to    specify desired position 9 a, wheel 10 b to specify desired course 9    b, velocity specification device 10 c to specify desired velocity,    etc.-   11: One or more command signal lines or a communication bus for    command signals (9) to the control system (2).-   12: One or more sensor signal lines or a communication bus for    sensor signals (7) to the control system (2).-   13: Control signals including shaft speed (13 a, 13 b) for propeller    (16) and thruster (17) and angle (13 c) for rudder (18) or thruster    (17),-   13′ Control signals that are sent to the remote test laboratory (40)-   14: One or more third signal lines (14) or communication bus from    the control system (2) to the actuators (3) (16, 17, 18)-   15: Data logger.-   16: Propeller (16)-   17: Thruster (17),-   18: Rudder (18): (together “actuators” (3).-   19: Status signals-   30: Vessel simulator in remote test laboratory (40)-   31: Control algorithm (31) for the computation of control signals    (13) to the vessel actuators (16, 17, 18) on basis of sensor signals    (7), command signals (9) and the dynamic parameters (5) of the    vessel (4), for sending of control signals (13) over a signal line    (14) to the actuators (3), for example propellers (16), thrusters    (17) or rudders (18).-   32: Algorithm in vessel simulator (30) for the computation of the    dynamic motion of the vessel on basis of simulated sensor signals    (7), vessel parameters (5), simulated wind speed and wind direction,    simulated wave elevation and wave direction, simulated current speed    and current direction, etc, and the forces of the actuators (3) on    the vessel.-   40: A remote test laboratory

1. A method for testing a control system (2) in a vessel (4), in whichsaid control system (2) comprises control and monitoring of said vessel(4) with control signals (13) to one or more actuators (3), said methodcomprising the following sequential steps: acquisition in real time ofsensor signals (7) to said control system (2) from one or more sensors(8) over a first sensor signal line (12) to said control system (2);acquisition of command signals (9) to said control system (2) from acommand input device (10) over a second signal line or command signalline (11) to said control system (2); computation in a control algorithm(31) in said control system (2) on basis of one or more of said sensorsignals (7) and said command signals (9), and sending of said controlsignals (13) over a third signal line (14) to said actuators (3)characterised by disconnection of one or more of said sensor signals (7)from one or more of said sensors (8) or of said command signals (9) fromsaid control input devices (10), so that the selected sensor signals (7)or command signals (9) do not flow to said control system (2), andreplacement of one or more of said disconnected sensor signals (7) orsaid command signals (9), with corresponding simulated sensor signals(7′) or simulated command signals (9′) that are generated in a remotetest laboratory 40) with respect to said vessel (4) and are sent over acommunication line (6) over one or more of said signal lines (12, 14) tosaid control system (2); continued computation in said control system(2) on basis of said real and/or said simulated sensor signals (7 a or 7a′, 7 b or 7 b′, 7 c or 7 c′, . . . ) or said real and/or said commandsignals (9 a or 9 a′, 9 b or 9 b′, 9 c or 9 c′, . . . ) of controlsignals (13′), and sending of said control signals (13′) over saidcommunication line (6) to said remote test laboratory (40).
 2. Themethod of claim 1, comprising simulation in a simulator (30) in saidtest laboratory (40) by means of an algorithm (32) of a new dynamicstate of a vessel model (4′) on basis of said control signals (13′). 3.The method of claim 1, in which said sensor signals (7) comprise one ormore of the following sensor parameters from said sensors (8): aposition (7 a) of said vessel from position sensors (8 a), such as GPSreceivers (8 a); hydroacoustic position sensors (8 h), integratingacceleration sensors, etc.; a course (7 b) from course sensors (8 b),e.g. a gyrocompass or some other compass; a velocity (7 c) from avelocity sensor (8 c) or an integrating acceleration sensor; a windspeed (7 d) and a wind direction (7 e) from an anemometer (8 d, 8 e); aroll angle (7 f) from a roll angle sensor (8 f); a pitch angle (7 g)from a pitch angle sensor (8 g).
 4. The method of claim 1, in which saidcontrol signals (13) comprise signals (13 a, 13 b, 13 c) in the form ofshaft speed (13 a, 13 b) for one or more propellers (16) or thrusters(17), and angles (13 c) for rudder (18) or thrusters (17) and possibleother control devices to achieve one or more of desired position (9 a),course (9 b), velocity (9 c).
 5. The method of claim 1, in which saidpropellers (16) comprise one or more propellers (16 a, 16 b, 16 c, . . .).
 6. The method of claim 1, in which said control devices (18) compriseone or more rudders (18 a, 18 b).
 7. The method of claim 1, in whichsaid control devices (18) comprise one or more thrusters (17).
 8. Themethod of claim 1, in which said command input device (10) comprises atleast one position specification device (10 a), a wheel (10 b), avelocity specification device (10 c), or a device for specification ofdesired roll angle, pitch angle, heave compensation, etc. 10 x) thatgives a command signal for one or more of desired position (9 a),desired course (9 b), and desired velocity (9 c) or some other desiredvariable (9 x), e.g. desired roll angle, desired pitch angle, desiredheave compensation, etc.
 9. The method of claim 1, in which said remotetest laboratory (40) is used to verify that said control signals (13,13′) from said control system (2) on basis of said simulated sensorsignals (7′) and said simulated command signals (9′) in a test, andpossibly remaining real sensor signals (7) and remaining real commandsignals (9), are such that said control signals (13, 13′) will lead to adesired state of said vessel (4), and where said control system (2) iscertified on basis of this.
 10. The method of claim 1, in which thecomputation in said control algorithm (31) of said control system (2)uses dynamic parameters (5) of the vessel, including mass (m), the axialmoments of inertia of the vessel, the mass distribution of the vessel,and hull parameters that determine the geometry of the hull.
 11. Themethod of claim 1, in which the disconnection of said sensor signals (7)from said sensors (8) to said control system (2) is done by means of aswitch (15 a) on said signal line (12).
 12. The method of claim 1, inwhich the disconnection of said command signals (8) from said commandinput device (10) to said control system (2) is done by means of aswitch (15 b) on said signal line (11).
 13. The method of claim 1, inwhich said remote test laboratory (40) is located on land, and wheresaid vessel (4 a, 4 b, 4 c, . . . ) that is being tested is situated ata long distance from said test laboratory (40), typically between 1 and20000 km, and where the vessel that is tested is in a harbor, in a dockor a yard, moored, or at the open sea.
 14. The method of claim 1, inwhich failure situations are tested by disconnection one or more ofselected signals at the time of said sensor signals (7) or said commandsignals (9) to simulate breakdown of components, and where the responseof the control system in the form of said control signals (13, 13′) andstatus signals (19, 19′) are logged on a logger (15) in said remote testlaboratory (40).
 15. The method of claim 1, in which failure situationsare tested by changing or generating disturbances in a selection of saidsimulated sensor signals (7′), or by generating external disturbanceslike weather, wind, electrical noise to said simulated sensor signals(7′) that are sent from said remote test laboratory (40) to said controlsystem (2) in said vessel (4), and where the response of said controlsystem (2) in the form of said control signals (13, 13′) and said statussignals (19, 19′) are logged on said logger (15) in said remote testlaboratory (40).
 16. The method of claim 1, in which new software forsaid control system (2) on board said vessel (4) is sent from saidremote test laboratory (40) over said communication line (6).
 17. Themethod of claim 1, in which said remote test laboratory (40) on basis ofa test of said control system (2) and the test result, is used toapprove said control system (2) and to certify said control system (2)for regular use in said vessel (4).
 18. A system for testing a controlsystem (2) in a vessel (4), said control system (2) being arranged tocontrol and monitor said vessel (4), comprising the following features:one or more sensors (8) on board said vessel (4) to send one or moresensor signals (7) over a signal line (12) to said control system (2),command input devices (10) on board said vessel (4) arranged to send oneor more of desired position, course, velocity (9) etc. over a commandsignal line (11) to said control system (2), an algorithm (31) in saidcontrol system (2) for the computation of control signals (13) to vesselactuators (3) on basis of said sensor signals (7), said command signals(9), for sending of said control signals (13) over a signal line (14) tosaid actuators (3), characterised by one or more communication lines (6)for sending of one or more simulated sensor signals (7′) and/orsimulated command signals (9′) from a remote test laboratory (40) tosaid control system (2); a simulator (30) including an algorithm (32)for the simulation of new sensor signals (7′) of a vessel model (4′)based on the previous state (7, 7′) said control signals (13, 13′), anddynamic parameters (5) for said vessel (4), in which said communicationline (6) is arranged for sending back said new simulated sensor signals(7′) of said vessel model (4′) to said control system (2), for continuedcomputation in said control system (2) on basis of the real and/orsimulated values of said sensor signals (7, 7′) or the real or simulatedvalues of said command signals (9, 9′), of said control signals (13) toachieve at least one of said desired position, course, velocity (9)etc., and in which said communication line (6) is arranged for sendingof the response from said control system (2) in the for of said controlsignals (13) as control signals (13′) to said remote test laboratory(40).
 19. The system of claim 18, comprising a switch (15 a) is arrangedto disconnect one or more of said sensor signals (7) from said signalline (12) to said control system (2).
 20. The system of claim 18,comprising a second switch (15 b) is arranged to disconnect one or moreof said command signals (10) from said command signal line (11) to saidcontrol system (2).
 21. The system of claim 18, comprising a thirdswitch (15 c) is arranged to disconnect one or more of said controlsignals (13) from said signal line (14) from said control system (2).22. The system of claim 18, in which said dynamic parameters (5) of saidvessel (4) enter into said algorithm (31) of said control system (2) forthe computation of said control signals (13) to said actuators (3). 23.The system of claim 18, in which said remote test laboratory (40) isprovided with a simulator (30).
 24. The system of claim 18, in whichsaid communication line (6) for sending of one or more of said simulatedsensor signals (7′) from said remote test laboratory (40) is arranged tobe connected to and disconnected from a first real-time interface (6 a),on said remote test laboratory (40).
 25. The system of claim 18, inwhich said communication line (6) is arranged to be connected to anddisconnected from a second real-time interface (6 b) on said vessel (4),and where said second real-time interface (6 b) is arranged to beconnected to said signal line (11) to said control system (2) throughsaid switch (15 a).
 26. The system of claim 18, comprising a simulatedcommand input device (10′) for sending of said simulated command signals(9′) from said remote test laboratory (40) through said real-timeinterface (6 a) and over said communication line (6) and through saidreal-time interface (6 b) to said control system (2).
 27. The system ofclaim 18, in which the entire of or parts of said algorithm (31) in saidcontrol system (2) is arranged to be modified, calibrated or replacedover said communication line (6) from said remote test laboratory (40).28. The system of claim 18, in which said control signals (13) includesignals (13 a, 13 b, 13 c) in the form of shaft speed (13 a, 13 b) forone ore more propellers (16) or thrusters (17), and angles (13 c) forrudders (18) or thrusters (17) or possibly other control devices. 29.The system of claim 18, wherein said sensors (8) include one or more ofthe following: position sensors (8 a), to determine a position (7 a), ofsaid vessel (4) such as a GPS receiver (8 a), hydroacoustic positionsensors (8 h), integrating acceleration sensors, etc.; course sensors (8b), to determine a course (7 b) of said vessel (4), e.g. a gyrocompassor some other compass, a velocity sensor (8 c) or an integratingacceleration sensor to determine a speed (7 c) of said vessel (4); ananemometer (8 d, 8 e) to give (relative) wind speed (7 d) and winddirection (7 e); a roll angle sensor (8 f) to give a roll angle (7 f); apitch angle sensor (8 g) to give a pitch angle (7 g).
 30. The system ofclaim 18, wherein said remote test laboratory (4) includes a data logger(15) for logging of the response in the form of said control signals andstatus signals (13′, 19′) from said control system (2) to said sensorsignals (7, 7′).